Non-invasive medical techniques have greatly increased the ease and success with which diagnostic and surgical procedures can be performed. As just one example, the treatment of pulmonary cancer has been advanced by the development of resector balloon catheters, such as that disclosed in U.S. Pat. No. 8,226,601 to Gunday et al., the specification of which is hereby incorporated by reference herein in its entirety.
In order to perform such non-invasive procedures, devices must be employed that allow the internal anatomy of the patient to be viewed by the medical practitioner. Accordingly, various types of imaging devices, employing a wide variety of optical assemblies, have been used for this purpose. However, because the interior of the human body is almost completely dark, proper illumination of the target site inside the body is required in order to obtain useful images. Specifically, light must be delivered to the interior body, into the field of view of the imaging device, such that the reflected light can be captured and transmitted to an appropriate device for rendering those images.
In traditional operating environments, light is transmitted from an external light source into the patient. Since these light sources must be very bright in order to provide sufficient illumination for imaging, they tend to generate significant heat. Since they generate so much heat, which could damage any biological tissue with which they come into contact, it is common to use self-contained, external light sources. A typical example of this is described in U.S. Pat. Nos. 7,668,450 and 8,246,230 to Todd et al. As described therein, a typical light source unit includes a light bulb, a ballast power supply, controls, and cooling fans. These light source units are typically mounted on a rack or boom arm along with other self-contained units, such as camera control units, insufflators, and electrosurgical units. The light generated by this light source in supplied through a light guide, such as a fiber optic cable, which transmits the light to the instrument being used in the patient.
These light sources, which require a lot of space and power, have a number of disadvantages. First, they are inefficient, as they must generate extremely intense light in order to compensate for the distance the light must travel along the cable from the unit to the instrument. Additionally, they can create dangerous conditions by transmitting heat energy to the patient. Further, the light cable is both cumbersome and further adds to the hazard of having too many cables in an already crowded room that can trip the medical professional or supporting personnel.
Accordingly, it has been proposed to instead use LEDs as a source of illumination. Because they are so small, they can be integrated into the imaging device, much closer to the target site, and their high light output, low cost, longevity, and reliability make them a desirable solution.
However, LED based light sources can get very hot during operation, and thus, can cause burns and equipment damage due to these high operating temperatures. These problems are very prominent when the light source is integrated in a portable or handheld medical device, which the LED will heat up. This can be hazardous for the patient, who will be in direct contact with the hot imaging device or instrument housing the LED, or possibly the hot LED itself, which can result in burns. Likewise, the medical practitioner holding the medical device can likewise be burned, resulting in injury to the practitioner, as well as serious injury to the patient if the practitioner unexpectedly moves or drops the instrument as a result. Additionally, heat can damage the device housing the LED, such as the optical elements of the imaging device.
What is desired, therefore, is a light source that is sufficiently bright to illuminate the interior of a patient. What is further desired is a light source that can be incorporated into the medical imaging device being used on the patient. What is also desired is a light source that will not result in burns to the patient or medical practitioner.